The results of this investigation into late inoculation effects of ductile irons show that the simultaneous addition of O and S with a proprietary alloy blend greatly improves in- oculation response and properties compared with standard Ca-bearing FeSi75. Similar behaviour was also identified in low sulphur grey cast irons.36
When the mole fractions of the
active ingredients in both inoculants are taken into consider- ation, the complex inoculant contains almost seven times the active nucleating elements that are present in foundry-grade FeSi75. Secondly, the OS-IE inoculant technology appears to provide a clean, fresh source of sulphur and oxygen.
The combination of fresh sulphur and oxygen allows the other proprietary inoculating elements (calcium, aluminum, et. al) to react in-situ and provide multiple times the nucle- ation sites of other, less potent inoculants. Thus, it is not surprising that such a significant reduction in inoculant addi- tion levels occurred.
(a)
Figure 11 illustrates the mass and volume of a 7.5 gram proprietary OS-IE inoculant (which has been formed into a tablet) compared to 75 grams of foundry grade FeSi75, the same 1 to 10 ratio of the OS-IE inoculant to FeSi75 that was used in the experiments.
(b)
Figure 9. Nodular graphite in 0.2wt-% FeSi75 and 0.01wt-% Complex Alloy (OS-IE) inoculated ductile irons, at different distance (d) of the apex of W31/2
wedge sample.
(c)
Alloy (OS-IE) in-mould inoculated ductile iron. 76
Figure 8. Chill tendency (a) carbides amount (b) and pearlite amount (c) at 10, 25 and 40 mm distances from the apex of W31/2
wedge sample of FeSi75 and Complex
Figure 10.
Brinell hardness of Un-Inoculated and In- mould inoculated irons (20 mm/0.79in diameter bars).
International Journal of Metalcasting/Volume 8, Issue 2, 2014
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